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TEMPERATURE AND THE COORDINATION OF CELL CYCLES WITHIN THE ROOT MERISTEM OF ALLIUM SATIVUM L.
Author(s) -
TAYLOR A. T.,
CLOWES F. A. L.
Publication year - 1978
Publication title -
new phytologist
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.742
H-Index - 244
eISSN - 1469-8137
pISSN - 0028-646X
DOI - 10.1111/j.1469-8137.1978.tb01642.x
Subject(s) - meristem , biology , cell cycle , mitosis , botany , root cap , allium sativum , biophysics , horticulture , microbiology and biotechnology , cell , shoot , biochemistry
SUMMARY Cell cycling has been surveyed throughout the meristem over a range of temperature by stathmokinetic and DNA‐labelling methods. There is a quiescent centre of ninety cells either out of cycle or with prolonged cycles. The cap initials have the highest rate of cell production, but only over a short temperature range. Outside that range the distal stelar cells have higher rates. The numbers of cells in the cap and its initials fall off with increasing temperature and there is a twelve‐fold variation in the rate at which the initials can refurnish the cap with new cells. The reduction in cell production that occurs towards the proximal margin of the meristem is due solely to lowering the growth fraction and the meristem contracts at high temperatures. The phases of the cycle as fractions of the whole vary from region to region and with temperature in the same region. G1 is the most variable phase though it is never eliminated as it is in Zea and the shortening of the mean cycle of cycling cells in the stele from the tip to the proximal margin of its meristem is brought about largely by the reduction of G1 and, to a lesser extent, of G2 while both S and M lengthen. S and M decrease as the temperature increases from 20 to 30°C while G1 and G2 are minimal at 25°C. The coordination of cycle parameters in Allium is discussed in relation to the anatomical features of its meristem and contrasted with that in Zea.